Conventionally, an electrical component system in an automobile employs a circuit assembly such as a junction box that supplies, blocks, or distributes power from a battery, for example, and a wire harness that electrically connects various kinds of devices including such a circuit assembly to each other, so that efficient electrical wiring is realized.
Particularly due to demand for electrification of vehicles in recent years, the types and the number of circuit assemblies and wire harnesses that are to be employed are on the rise. For example, as disclosed in JP2016-220475A, in electric vehicles, hybrid cars, plug-in hybrid cars, and the like in recent years, a battery pack that includes a battery module and a junction box is provided under the floor of the seat, for example, and the junction box of the battery pack and an external PCU (Power Control Unit) or a charger need to be connected to each other using high-voltage wire harnesses that have a larger diameter than usual. Also, as disclosed in JP2016-220475A, two or more junction boxes are employed in some cases.
However, as the types and the number of circuit assemblies and wire harnesses increase, the number of steps for connecting wire harnesses to circuit assemblies via connectors or the like increases, and there is a problem in which workability degrades when a vehicle is assembled. Furthermore, due to demand to, for example, downsize a vehicle, it is necessary to more densely arrange a plurality of circuit assemblies and wire harnesses to which the circuit assemblies are connected. Therefore, it is possible to conceive of the idea of arranging two circuit assemblies adjacent to each other to save space. However, it is necessary to secure space in which wire harnesses and connectors are to be arranged, and there are limitations in saving space.